Lurker Eigenbolt - good for mini and axe. http://www.lurkerpb....-eigenbolt-kit/ - This is the only bolt that is actually redesigned for increased performance. The boss is an excellent product but it is just a nicer version of the stock bolt. Same with the techT. The Lurker is superior for many reasons that are all covered on their website.

Tried them all in my axe. Tech T (ok, but not worth the money with other better cheaper options available).
Boss bolt xsv more consistent however tended to stick to much, thereby decreasing smoothness. Lurker, interesting install, however smoothest of all bolts thereby leading to more consistent ball flight. Dwell settings on my axe are higher then Lurker recommends or it doesn't shoot very well. Combined this with a Lurker barrel and I have had a lot of comments from tournament players on how quite this set is. One ref did not even hear me shoot someones shoe from 10 feet away. I had to call a paintcheck on the guy. Overall, smoothness is what you are trying to achieve, been down this road....choose Lurker 1st, boss 2nd. Or try both as there is a blurker set up out there I have not tried.

Basically, you take the Boss bolt spacer and add it to a Lurker bolt. You'll also see in that post that after getting feedback from the users that Lurker started adding a flat o-ring to his package to accomplish the same result. I do not know of anyone that's tried both the Boss spacer and the Lurker flat o-ring to see if it works as well. Users seemed to be very happy with the blurker performance.